Emojis in your subject line add visual interest and increase engagement with your recipients. But keep in mind that too many emojis can look like spam to a recipient's email filter. In most cases, it's best to stick with one or two. Learn more about best practices for adding emojis to your email subject line.
Emojis are supported by most major email clients, but they may render differently based on the recipient's email client, web browser, or operating system. For example, emojis may render in color for some recipients and in black and white for others.